Process for preparation of solid phase dispersion of photoconductive materials

ABSTRACT

Process for preparation of a solid phase dispersion of photoconductive materials in an insulating binder matrix from a film forming insulating polymeric resin and an organoselenium compound capable of undergoing selective decomposition in response to an appropriate stimulus; whereby, elemental selenium is extruded from said organo-selenium compound and deposited in the binder matrix. Because this extrusion/deposition of elemental selenium can be performed selectively, it is possible to prepare binder films having photoconductive image patterns which are suitable for use in range extended and conventional xerography.

This is a continuation, division, of application Ser. No. 454,896, filedMar. 26, 1974.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process, an article prepared according tosaid process and a method employing said article. More specifically,this invention involves a process for preparation of a solid phasedispersion of photoconductive materials within an insulating bindermatrix.

2. Description of the Prior Art

The formation and development of images on an imaging member ofphotoconductive materials by electrostatic means is well-known. The bestknown of the commercial processes, more commonly known as xerography,involves forming a latent electrostatic image on the imaging layer of animaging member by first uniformly electrostatically charging the surfaceof the imaging layer in the dark and then exposing thiselectrostatically charged surface to a light and shadow image. The lightstruck areas of the imaging layer are thus rendered relativelyconductive and the electrostatic charge selectively dissipated in theseirradiated areas. After the photoconductor is exposed, the latentelectrostatic image on this image bearing surface is rendered visible bydevelopment with a finely divided colored electroscopic powder material,known in the art as "toner". This toner will be principally attracted tothose areas on the image bearing surface having a relative polarityopposite to the charge on the toner and thus form a visible powderimage.

The developed image can then be read or permanently affixed to thephotoconductor in the event that the imaging layer is not to be reused.This latter practice is usually followed with respect to the binder-typephotoconductive films where the photoconductive insulating layer is alsoan integral part of the finished copy. U.S. Pat. Nos. 3,121,006;3,121,007.

In so-called "plain paper" copying systems, the latent image can bedeveloped on the imaging surface of a reusable photoconductor ortransferred to another surface, such as a sheet of paper, and thereafterdeveloped. When the latent image is developed on the imaging surface ofa reusable photoconductor, the developed image is subsequentlytransferred to another substrate and then permanently affixed thereto.Any one of a variety of well-known techniques can be used to permanentlyaffix the toner image to the transfer sheet, including overcoating withtransparent films and solvent or thermal fusion of the toner particlesto the supportive substrate.

In the most popular of the xerographic systems of the type referred toabove, the imaging member comprises a photoconductive insulating layerof amorphous selenium on a suitable conductive substrate. Suchphotoconductive insulating layers are generally prepared by vacuumdeposition of selenium under carefully controlled conditions. Thesevacuum deposition techniques do not readily lend themselves to thecontinuous manufacture of photoconductive imaging members. Even undercarefully controlled conditions, vacuum deposition of photoconductiveinsulating layers of amorphous selenium is often beset withdifficulties. For example, lack of uniformity in deposition can lead toso-called "pin holes" in the selenium layer. Spattering of moltenselenium from the crucible in the deposition chamber has also been knownto cause uneven deposition and blemishes in the surface of the imaginglayer. Nor is it uncommon for the vacuum deposition chamber to becontaminated with dust particles which codeposit along with the seleniumon the receptive substrate thus forming additional imperfections in thesurface of imaging layer. In addition to the technique described above,a number of alternative procedures have been disclosed for preparationof selenium and selenium containing films. Representatives of suchalternative procedures include the electrochemical deposition ofselenium from a suitable electrolyte (U.S. Pat. Nos. 2,649,409 and2,414,438) and the chemical deposition of a metal selenide film from asolution containing a metal salt, selenourea and other ingredients,Chem. Abstr. 79, 84806j (1973). Although such electrochemical andchemical deposition procedures can provide very precise control overboth the rate and uniformity of deposition selenium and metal selenidefilms, neither system has received general commercial acceptance.

Recently, a number of alternative photoconductive insulating layers havebeen disclosed wherein a photoconductive pigment is (a) dispersed in acharge carrier transport matrix, (UK Pat. No. 1,343,671, which in turnclaims priority to U.S. application Ser. No. 371,646, filed June 20,1973) or an electronically inert binder U.S. Pat. No. 3,787,208 or (b)sandwiched between a conductive substrate and a charge carrier transportlayer, UK Pat. No. 1,337,228 (which in turn claims priority to U.S.application Ser. No. 94,139, filed Dec. 1, 1970).

In the imaging members disclosed in previously referenced UK Pat. No.1,343,671, the carrier generation and transport functions are separatedand, thus, it is possible to prepare photoconductive insulating layershaving less than 10 parts by weight selenium in the imaging layer of thephotoreceptor while retaining electrophotographic speed at leastcomparable to that of amorphous selenium alone. Since the photoactivematerial, (e.g. a selenium pigment), is dispersed in the insulatingresin, the method for preparation of photoconductive insulating layersfrom such dispersions can follow generally accepted coating techniquesapplicable to such resinous materials. The simplicity of such procedurescan be readily adapted to a continuous manufacturing process therebyincreasing the efficiency of preparation of such photoconductors. Inpreparation of such binder layers, a photoactive pigment and anelectronically active insulating binder resins are dispersed in anappropriate solvent and the resulting dispersion cast or coated on aconductive substrate to the desired film thickness. The resulting filmcontains a random distribution of photoactive particles throughout acharge transport matrix.

Carrier generation and transport functions can also be separated innon-binder photoreceptor systems (UK Pat. No. 1,337,228) simply byovercoating a thin layer of amorphous selenium with an electricallyactive matrix, such as poly-(N-vinylcarbazole). In the dark, theovercoating is sufficiently insulating to support a sensitizing surfacecharge, (relieving the selenium layer from performing this function),and thus allowing the use of a selenium photogenerator layer of reducedthickness. The overcoating also helps to mask surface imperfections inthe selenium layer.

Where it is possible to orient such photoconductive particles within asuitable binder (U.S. Pat. No. 3,787,208) the concentration of suchphotoconductive pigments can be further reduced without any compromisein the electrophotographic speed of the photoconductive insulatinglayer. The mechanism involved in the orientation of such photoconductivepigments in the above referenced application is analogous to thesituation existing in preparation of ceramic materials from refractorymixtures having a predetermined particle size distribution. In such asystem, the smaller particles are forced to occupy the spaces betweenthe larger particles. Although this system provides a degree of controlover the spatial distribution of photoconductive pigments within abinder layer, such control is a function of particle size distributionrather than an ordering of such materials in compliance with apredetermined arrangement or pattern.

The controlled distribution of chalcogenides within an amorphous glassymatrix has just recently been disclosed in German patent application OLS2,233,868 (priority being claimed to U.S. patent application Ser. No.163,891, filed July 19, 1971). This German application describes aseries of systems wherein a precursor (an "organo-elemento" compound) isinitially dispersed in the amorphous glassy matrix and chalcogenidesselectively extruded therefrom in response to (a) exposure to imagingenergy followed by exposure to development energy; (b) simultaneousexposure to both the imaging and the development energy; or (c) exposureto imaging energy. The glassy matrix within which such chalcogenidedeposition takes place must be capable of trapping of the intermediatecompounds, radicals and charge carriers generated during exposure toimaging energy in order to enable subsequent thermal development and/orenhancement of the desired chalcogenide deposit. Chalcogenide formationis manifest within the glassy matrix by the appearance therein of apermanent, dense and highly visible deposit.

Accordingly, it is the object of this invention to provide a process forpreparation of a solid phase dispersion of selenium in an organicpolymeric matrix.

More specifically, it is the object of this invention to provide aprocess for preparation of a photoconductive insulating layer comprisinga solid phase dispersion having randomly dispersed selenium particlesthroughout an electrically inert polymer matrix.

Another object of this invention is to provide a process for preparationof a photoconductive insulating layer comprising a solid phasedispersion having randomly dispersed selenium particles throughout apolymer matrix which is capable of efficient transport of chargecarriers of at least one polarity.

Yet another object of this invention is to provide a process forpreparation of a photoconductive insulating layer having substantiallytwo separate and highly localized phases, one phase comprising aphotogenerator layer and a second phase comprising a charge carriertransport layer.

Still yet another object of this invention is to provide a series ofarticles prepared by the above processes.

Additional objects of this invention include the use of these articlesin one or more imaging methods.

SUMMARY OF THE INVENTION

The above and related objects are achieved by providing a process forpreparation of a solid phase dispersion comprising selenium particles inan insulating polymeric matrix. In this process, a selenium precursorcan be initially combined with a film forming polymeric material in anappropriate solvent and the resulting dispersion or solid solutionformed into a film either on or independent of a supportive substrate.The selenium precursor in such films is an organo-selenium compoundwhich, upon exposure to electromagnetic radiation of the appropriatewavelength, is capable of undergoing substantial carbon-selenium bondscission whereupon elemental selenium is extruded from said compound anddeposited within the polymer film in substantial conformity with thedistribution of electromagnetic radiation throughout said film. In thepreferred embodiments of the process of this invention, the solid phasedispersion can be substantially depleted of selenium particles by simplyheating said dispersion to a given temperature for the requiredinterval.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic representation of an embodiment of animaging method according to the invention;

FIG. 2 is a photomicrograph of a solid phase dispersion preparedaccording to the invention;

FIG. 3 is a photomicrograph of another solid phase dispersion preparedaccording to the invention; and

FIG. 4 is a photomicrograph of still another solid phase dispersionprepared according to the invention.

DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS

The source of elemental selenium in the process of this invention(hereinbefore and hereinafter referred to as "selenium precursor"compounds) can be selected from a limited number of materials which arecapable of undergoing a decomposition reaction in response to anappropriate stimulus (preferably ultraviolet light) and yielding, as oneof the products of such decomposition, elemental selenium. Theby-products of such decomposition reaction must also be compatible withboth photogeneration and transport of charge carriers within the filmand preferably assist in the photogeneration and/or transport of suchcharge carriers. Precursor compounds which have proven themselves highlyuseful in the process of this invention include organo-selenides of theformula

    R -- (Se).sub.n -- R.sub.1

wherein

R and R₁ are independently selected from the group consisting of benzyl,alkyl substituted benzyl, alkoxy substituted benzyl, acyl substitutedbenzyl, amino substituted benzyl, amido substituted benzyl, arylalkylsubstituted benzyl, aryl substituted benzyl, alkoxy alkyl substitutedbenzyl, aryloxy alkyl substituted benzyl, amino alkyl substitutedbenzyl, hydroxy alkyl substituted benzyl, alkyl amino substitutedbenzyl, aryl amino substituted benzyl, alkyl carbonyl substitutedbenzyl, alkyl thio substituted benzyl, alkyl seleno substituted benzyl,carboxamido substituted benzyl, halogen substituted benzyl, carboxylsubstituted benzyl, cyano substituted benzyl, and nitro substitutedbenzyl; alkyl, alkoxy, amino substituted alkyl, amido substituted alkyl,aryl alkyl, alkoxy alkyl, aryloxy alkyl, hydroxy substituted alkyl,carbonyl substituted alkyl, thio substituted alkyl, seleno substitutedalkyl, carboxamido substituted alkyl, halogen substituted alkyl, carboxysubstituted alkyl, cyano substituted alkyl, and nitro substituted alkyl;cyclo alkyl and substituted cyclo alkyl; heterocyclic radicals; and acylradicals; and

n is 1 to about 4.

Many of the compounds within the scope of the above formula are readilyavailable from commercial sources and where not so available can beprepared by methods disclosed in the technical literature. For example,symmetrical dialkyl selenides can be prepared by the reaction of analkyl halide with sodium selenide, M. L. Bird et al, J. Chem. Soc., 570(1942); R. Paetzold et al, Z. Anorg. Allg. Chem., 360, 293 (1968). Themost common method for preparation of unsymmetrical dialkyl selenides isa modified Williamson synthesis, H. Rheinboldt, "Houben -- WeylMethodender Organischen Chemie", Volume IX, E. Muller, Ed., Georg ThiemeVerlag, Stuttgart, p. p. 972, 1005, 1020, and 1030 (1955).

Diselenides within the scope of the above formula can be prepared byalkaline hydrolysis of organo selenocyanates (H. Bauer, Ber., 46, 92(1913)) or selenosulfates (W. H. H. Gunther and M. N. Salzman, Ann. N.Y., Acad. Sci., 192, 25 (1972)). The preparation of unsymmetricaldiselenides suitable for use as selenium precursor compounds aretypically prepared by reaction of organic selenyl bromides with organicselenols, H. Rheinboldt and E. Giesbrecht, Chem. Ber. 85, 357 (1952).Heterocyclic selenium precursor compounds capable of undergoingsubstantial carbon-selenium bond scission upon irradiation withultraviolet light can be prepared by reaction of organic bromides withorganic selenates, L. Chierici et al, Ric. Sci., 25, 2316 (1955).

Polyselenides (n equal to 3 or 4) can also be readily prepared bytechniques disclosed in the literature For example, aromatictriselenides can be synthesized by reaction of aromatic selenenylselenocyanates with thiols, H. Rheinboldt et al, Chem. Ber. 88, 1(1955).

A second class of selenium precursor compounds which is suitable for usein the process of this invention can be represented by the followingformula ##STR1## wherein

R and R₁ are the same as previously defined for compounds R -- (Se)_(n)-- R₁ in addition to aryl and substituted aryl,

n is 1 or 2.

Diacyl and diaroyl selenides within the scope of the above formula canbe prepared by reaction of acyl chlorides with hydrogen selenides, K. A.Jensen et al, Acta. Chem. Sand., 26, 1465 (1972).

A third class of precursor compounds which can be used in the imagingprocess of this invention include the tetravalent selenium compoundsrepresented by the formula: ##STR2## wherein

R₂ and R₃ are independently selected from the group consisting of arylor substituted aryl radicals and

x and y are independently selected from the group consisting of halogen,hydroxyl, alkanoyloxy or aroyloxy.

Dichloroselenides of the above formula can be prepared either byreaction of methylaryl ketones with selenium tetrachloride or reactionof methylaryl ketone with selenium oxychloride; F. Kunckell et al,Justus Liebigs Ann. Chem. 314, 281 (1901); and R. E. Nelson et al, J. M.Chem. Soc. 52, 1588 (1930).

A fourth class of selenium precursor compounds which are suitable foruse in the method of this invention include many of the seleniumanalogues of amides, biurets, carbazones, carbazides, esters,cyanoesters, selenoesters, semicarbazones, semicarbazides, ureas,substituted analogues thereof and heterocyclics containing theseanalogues as a component of the heterocyclic moeity. Compounds of thetype described above can be readily prepared by methods reported in"Organic Selenium Compounds", Klayman and Gunther, Ed., Chapter VII pp.273 - 303, John Wiley and Son (1973).

Selenoureas which are suitable for use in the process of this inventioninclude compounds of the formulae ##STR3## wherein

R, R', and R"' are independently selected from the group consisting ofhydrogen, alkyl, substituted alkyl, aryl or substituted aryl; and

X is a divalent organic radical capable of making up the balance of theheterocyclic ring.

Selenobiurets which are suitable for use in the process of thisinvention include compounds of the formulae ##STR4## wherein

R, R', R", R"' and R^(iv) are independently selected from hydrogen,alkyl, substituted alkyl, aryl or substituted aryl.

Selenocarbazides and semicarbazides which are also capable of undergoingsubstantial selenium-carbon bond scission in response to an appropriatestimulus include compounds of the formulae ##STR5## wherein

R, R', R", R"', R^(iv) and R^(v) are independently selected fromhydrogen, alkyl, substituted alkyl, aryl or substituted aryl.

Selenocarbazones and semicarbazones which also useful as seleniumprecursor compounds in the process of this invention include compoundsof the formulae ##STR6## wherein

R, R', R", R"', R^(iv) and R^(v) are independently selected fromhydrogen, alkyl, substituted alkyl, aryl or substituted aryl.

Additional selenium analogues of carbonyl compounds which are suitableas selenium precursors in the process of this invention include suchheterocyclic compounds as the selenium analogues of uracil. Where acarbonyl compound has more than one carbonyl function, seleniumreplacement of the carbonyl oxygen atoms may occur at one or more suchsites.

A fifth class of selenium precursor compound which is suitable for usein the process of this invention includes compounds of the formula

    R -- Se -- CN

wherein R is the same as previously defined for the compounds

    R -- (Se).sub.n -- R.sub.1

compounds of the above formula can be prepared by any one of a number oftechniques disclosed in the literature. For example, such compounds canbe prepared by the reaction of a cyanoselenyl radical with an alkyl oran arylalkyl halide; or by reaction of an aromatic diazonium salt with aselenocyanate ion; or the reaction of aromatic compounds bearing anactivating substituent (such as an amino or hydroxyl group) withdiselenodicyanide. These syntheses are more completely described inChapter IV of the previously referenced text entitled "Organic SeleniumCompounds".

The film forming insulating polymeric material used in combination withone or more of the above selenium precursor compounds in formation ofthe solid phase dispersions of this invention can be virtually andthermoplastic resin or elastomer which is both chemically compatiblewith one or more of the previously described organo selenium compoundsand is capable of transmitting the energy necessary for initiating thedesired decomposition reaction. Especially preferred polymeric materialswhich can be used in such solid phase dispersions include those polymerscapable of transport of charge carriers generated by the elementalselenium and the other products of the decomposition reaction. Typicalof such preferred materials are poly(N-vinylcarbazole),poly(vinylpyrene) and poly(N-ethyl-3-vinylcarbazole). Electronicallyinert polymers which are also suitable for use in such solid phasedispersion include polystyrene, poly(alkyl acrylates), poly(alkylmethacrylates), cyanoethyl starch, cyanoethyl cellulose, celluloseacetates, poly(vinylformal), poly(vinylacetal), poly(vinylbuteryl),poly(butadiene), poly(dimethylsiloxane), poly(esters), their respectiveblends and copolymers.

In preparation of the solid phase dispersion of this invention, it ispreferable to first dissolve the organo-selenium compounds andinsulating polymeric resin in a common solvent. The resulting solutionis then cast, sprayed, draw or dip coated on a supportive, preferablyconductive, substrate. The relative weight ratio of organo-seleniumcompounds to polymeric materials in the coating solution can range fromabout 10:90 to about 90:10 and preferably from about 20:80 to about30:70. The amount of solution transferred to the supportive substrateshould be sufficient to form a coating having a dry film thickness inthe range of from about 0.1 to about 100 microns. Any of the substratestraditionally used in combination with photoconductive insulating layersin electrophotographic imaging members can be coated with the abovesolution. Typical of such substrates include aluminum, chromium, nickel,metallized plastic films, metal coated plastic films, conductivecellulosic materials and metal oxide coated glass plates (e.g. NESAglass).

Alternatively, organo-selenium compounds may also be dispersed within apreformed, cross-linked film by swelling the latter in an appropriatesolvent also containing one or more of the previously definedorgano-selenium compounds. Upon evaporation of the solvent, theorgano-selenium compounds remaining entrapped within the polymer matrixas a fine molecular dispersion. Such cross-linked polymer films havedistinct and superior physical properties (e.g. abrasion resistance)when compared with films prepared from linear polymers. For example,highly cross-linked films are less soluble in many organic solvents,thus, permitting greater latitude in the casting or coating ofadditional layers thereon. Moreover, the more highly integrated networkof such films precludes both moisture from penetrating into its bulk andthe possible extraction of essential materials contained within thesefilms, (as may occur during liquid development and/or subsequentcleaning of the surface of these films).

Once having formed a polymer/precursor compound coating on thesupportive substrate in the manner described above, the coating isallowed to dry until substantially free of solvent residues used in itspreparation. This coating containing the organo-selenium compound canthen be subjected to a source of energy which is capable of effectingdecomposition products its elemental selenium. The manner oftransmission and type of energy employed to effect such decompositionreaction should not be sufficient to effect any substantial adversealteration in the polymeric materials present in the coating. The sourceof such energy can be electromagnetic radiation and/or thermal energy.In a typical embodiment of this invention, a polymeric coating preparedas described above is irradiated with sufficient ultraviolet light tocause uniform extrusion of elemental selenium along the surface of theirradiated film. The distribution of selenium in this film can vary withthe extent of distribution and depth of penetration of the extrusionenergy into the film. For example, during uniform ultraviolet lightillumination of a film containing a solid phase dispersion oforgano-selenium compound, most of the incident radiation will beabsorbed at or slightly below the surface of the film disposed proximateto the energy source. Upon absorption of this energy, selenium isextruded and deposited in substantial conformity with the distributionof this energy just below the surface of the film. As this depositionproceeds, the optical density of the film increases, thus, precludingpenetration of extrusion energy into the more remote depths of the film.Where the film thickness is substantially in excess of the depth ofpenetration of substantial amounts of extrusion energy, the resultingmember will not be suitable in conventional electrophotography due toinefficient photodischarge unless the polymeric matrix or some othermaterial in the film provides the necessary carrier transport acrossthat portion of the film which is substantially devoid of elementalselenium. The film thickness of such solid dispersions is, therefore, afunction of the carrier transport efficiency of the insulating polymermatrix and the intended end use of the resulting article. Generallyphotoextruded selenium films, wherein the polymer matrix iselectronically "inert", should have a thickness of about 2 microns, andpreferably somewhat less, in order to be suitable for use inelectrophotography. On the other hand, similarly photoextruded seleniumfilms, wherein the polymer matrix has good carrier transport properties(electronically "active"), can exceed 100 microns in thickness withoutany adverse effect on their electrophotographic properties.

After having initially subjected the solid phase dispersion toactivating electromagnetic radiation, it is possible to further alterthe physical form and quantity of the deposited selenium within thepolymer matrix merely by the application of heat at a predeterminedtemperature for an interval which is determined by the type and degreeof alteration desired. For example, an essentially uniform layer ofamorphous selenium located just below the surface of such a polymericfilm can be caused to contract or agglomerate into small compactspherical amorphous particles; such contraction or agglomerationoccuring at the site formerly occupied by the amorphous layer. Furtherheating to higher temperatures can cause the breakup of these particlesinto smaller particles and their wide spread dispersion throughout thepolymeric film. Prolonged heating of this dispersion, as in the casewhere the organo-selenium compound is dibenzyl diselenide, can result inessentially a reversal of the decomposition reaction and, thus, areduction in the concentration of elemental selenium within thepolymeric matrix. Reversal of the decomposition reaction will in someinstances result in reconstituting the selenium precursor compound. Itis also possible, however, to erase the elemental selenium depositwithout reversal of the decomposition reaction; that is withoutreconstituting the selenium precursor compound used in generation of thesolid phase dispersion. In this latter instance, such erasure can resultin the formation of another organoselenium compound. This new compound,in most instances, is capable of undergoing carbon-selenium bondscission in the same manner as the original precursor compound and thusthe reusable nature of the dispersion is preserved even though theselenium precursor compound may now differ from the one initiallyincorporated into the insulating polymer matrix. Where such selenium isdeposited along with or in the presence of other chalcogens (e.g.tellurium), the two elements may combine and thereby render subsequenterasure considerably more difficult or impossible.

Since the decomposition of the selenium precursor compound can beperformed selectively in response to a localized stimulus, it ispossible to prepare a photoconductive pattern of elemental seleniumwithin a polymer matrix merely by projecting a pattern of extrusionenergy onto a polymer film containing the precursor compounds. Thisphotoconductive pattern can be in the form of spaced dots or have ascreen type arrangement. Spaced dot photoconductors are suitable inpreparation of half tone reproductions and screen type photoconductorsare suitable for enhancing the solid density capability and extendingthe dynamic range of a photoconductive material, such as selenium. It isalso possible to project an image pattern onto a polymer film containingthese precursor compounds, and thus, produce a photoconductive imagepattern within said film. This imaged film can be used as a xeroprintingmaster. In each of the systems described above, it is possible tosubsequently "add on" additional information by merely projecting suchadditional information onto the previously exposed film.

The Examples which follow, further define, describe and illustrate theprocess of this invention. Apparatus and techniques used in this processand evaluation of the films prepared by this process are standard or ashereinbefore described. Parts and percentages appearing in such Examplesare by weight unless otherwise indicated.

EXAMPLE I Preparation of dibenzyl diselenide

A prerequisite to preparation of dibenzyl diselenide is the preparationof bis(methoxy magnesium)diselenide reagent. This material is preparedby placing about 3 grams (0.125 moles) magnesium turnings in a 1 literround bottom flask together with a small crystal of iodine. This mixtureis heated over a gas flame until the magnesium is "activated". About 200milliliters dry methanol is then introduced into the flask, the flaskfitted with a reflux condenser and a magnetic stirrer. The contents ofthe flask are heated to boiling under reflux conditions, and after theyellow iodine color has been discharged, about 7.9 grams (0.1 moles) dryselenium powder introduced into the mixture. The mixture is stirreduntil the initial vigorous reaction ceases and all solids have gone intosolution.

About 12.6 grams (0.1 moles) benzylchloride is now added by dropwiseaddition over a period of 15 minutes to the magnesium diselenidereagent. In about 5 to 10 minutes after the mixture of these materials,the reddish brown color of the solution appears discharged. Thissolution is diluted further by the addition of 200 milliliters water andthe addition of 10 milliliters concentrated hydrochloric acid. Uponcooling of this solution, the solids contained within the flask arecollected by filtration and recrystallized from ethanol. Yield: 14 gramsof yellow crystals (m. p. 94° C). Infrared spectral analysis of thismaterial confirms that it is dibenzyl diselenide.

A chloroform solution containing about 0.5 parts by weight dibenzyldiselenide (DBDS) and 3 parts by weightpoly(N-vinylcarbazole)--"Luvican", molecular weight 205,000,commercially available from BASF -- is coated on a flexible ball grainedaluminum plate using conventional draw bar coating techniques. Theequipment used in this coating procedure is a Gardner mechanical drivefilm coating apparatus which is equipped with an application bar havinga wet gap setting of 0.008 inches. The coated aluminum plate is placedin a hood for several hours and then transferred to a vacuum chamberwhere it remains overnight. Sufficient solution is transferred to thealuminum plate to provide a coating having a dry film thickness ofapproximately 10 microns. Upon substantially complete removal ofresidual chloroform from the coating, the coating is uniformlyirradiated with ultraviolet light from a distance of 6 inches for aperiod of 10 minutes. The source of ultraviolet irradiation is awater-cooled 450 watt Hanovia medium pressure mercury arc lamp. Thecoating on the aluminum plate turns reddish orange indicating thepresence of elemental selenium. The electrophotographic properties ofthe plate are now evaluated with a Xerox Model D processor. Aftercharging this plate in the dark to a positive potential of about 600volts, it is exposed to a light and shadow image by means of a Xerox No.4 camera; exposure being for 12 seconds at f 16. The latent image thusproduced is rendered visible by cascade development with a compositioncomprising Xerox 2400 Toner and 250μ steel MTP carrier. The toner imageis transferred from the plate to a positively charged paper substrateand fused thereto. Toner residues remaining on the surface of the plateare removed by wiping its surface with a wad of synthetic cotton-likematerial. The plate is then reprocessed in the same manner describedabove. Copy quality remains substantially the same throughout.

EXAMPLES II - X

The procedures of Example I are repeated except for variation in therelative concentration of dibenzyl diselenide to poly(N-vinylcarbazole).The table which follows indicates the effect that such variation inconcentration can have on xerographic print quality.

    __________________________________________________________________________    Composition of                                                                Coating Solution                                                                   DBDS PVK  wt.% of DBDS in                                                Example                                                                            wt.% wt.% Photoreceptor                                                                           Xerographic Print                                    __________________________________________________________________________    2    1    4    20.0      Good image, light                                                             background                                           3    0.5  5    9.1       Poor image                                           4    1    5    16.7      Fair to good image                                                            light background                                     5    2    5    28.6      Good image, no                                                                background                                           6    3    5    37.5      God image, moderate                                                           background                                           7    4    5    44.4      DBDS crystallized                                                             out                                                  8    1    10   9.1       No image                                             9    2    10   16.7      Good image, no                                                                background                                           10   3    10   23.1      Good image, light                                                             background                                           11   1    3    25.0      Good image, no                                                                background                                           __________________________________________________________________________

EXAMPLE XII Preparation of 4,4'-diseleno-dibutyric acid

Bis(methoxy magnesium) diselenide reagent is prepared in substantiallythe same manner as described in Example I. To this reagent is addedabout 10.1 grams (0.12 moles) butyrolactone, and the mixture heated toboiling under reflux conditions for 20 hours. At the end of thisinterval, the condenser is opened and the solvent within the flaskallowed to evaporate. Water is now added to the residues remaining inthe flask and the acidified solution extracted with ether. The yellowether solution is reextracted with sodium hydroxide and 4,4'-diselenodibutyric acid precipitated therefrom by the addition of hydrochloricacid. The precipitate is separated from the acidic medium andrecrystallized from carbon tetrachloride. Yield: 11 grams of plateletlike crystals, m. p. 88° C. Infrared spectral analysis of these crystalsconfirm them to be the desired product.

An electrophotographic imaging member is prepared in the mannerdescribed in Example I from 4,4'-diseleno butyric acid andpoly(N-vinylcarbazole). The imaging member thus prepared is evaluated bystandard electrophotographic techniques in the same manner described inExample I. Copy quality is satisfactory.

EXAMPLE XIII Preparation of α ,α' -diseleno-di-o-toluic acid

Bis(methoxy magnesium) diselenide reagent is prepared in the same mannerdescribed in Example I. About 13.4 grams (0.1 moles) phthalide is addedto this reagent and the resulting mixture heated to boiling under refluxconditions with agitation for 20 hours. At the end of this period, thecontents of the flask are allowed to cool, the clear supernatent liquidseparated from the solid by decantation and discarded. About 300milliliters water and 30 milliliters of 12 N hydrochloric acid areintroduced into the flask containing these solids, the solids thoroughlydispersed within these liquids and thereafter separated therefrom byfiltration. The solids are now dissolved in 2 N sodium hydroxide and thesolution aerated until precipitation of selenium is complete. Theselenium precipitate is removed by filtration and the clear orangefiltrate acidified with hydrochloric acid. Upon acidification, a yellowprecipitate forms which is dried over phosphorus pentoxide. The crudeproduct is purified by initially dissolving it in boiling methanol andthereafter allowing the resulting solution to stand at room temperaturefor several days; whereupon the purified product gradually crystallizesfrom solution. Yield: Yellow crystals, (m.p. 215°-218° C). Elementalanalysis confirms that the crystals are the desired product.

An electrophotographic imaging member is prepared in the mannerdescribed in Example I from α,α' -diseleno-di-o-toluic acid andpoly(N-vinylcarbazole). The imaging member thus prepared is evaluated bystandard electrophotographic techniques in the same manner described inExample I. Copy quality is satisfactory.

EXAMPLE XIV Preparation of dibenzyl selenide

Into a 250 milliliter 3 necked round bottom flask equipped with anaddition funnel and a magnetic stirring bar is placed 4.6 grams (0.058moles) of selenium powder and 50 milliliters of deoxygenated distilledwater. The flask is purged of air with nitrogen and a solutioncomprising 4.6 grams (0.122 moles) sodium borohydride in 50 millilitersof deoxygenated distilled water slowly added to the solution in theflask from the addition funnel. Upon contacting of these two solutions,vigorous hydrogen evolution occurs and the selenium powder is consumedthereby yielding a solution containing sodium hydrogen selenide. About14.6 grams (0.166 moles) benzylchloride is now introduced into the flaskand the resulting mixture stirred at room temperature for 18 hours. Thesolid product thus produced is collected by filtration washed with waterand recrystallized twice from pentane. Yield 11.81 grams of rod likecrystals, (m.p. 45° to 46° C).

An imaging member is now prepared from dibenzyl selenide andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XV Preparation of 2,2'-dipyridyl diselenide:

This compound is prepared according to the procedure described by H. G.Mautner, et al, J. Org. Chem. 27, 3671 (1962). The product of thissynthesis is crystallized from petroleum ether, (m. p. 47°- 48° C).

An imaging member is now prepared from 2,2'-dipyridyl diselenide andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XVI Preparation of 3,3'-di(2-methyl indolyl) diselenide:

This compound is prepared in the manner described by L. B. Agenas inArk. Kemi. 23, 157 (1964). Compounds prepared according to this methodhave a melting point of 183°- 184° C.

An imaging member is now prepared from 3,3'-di-(2-methyl indolyl)diselenide and poly(N-vinylcarbazole) in the manner described in ExampleI. This imaging member is evaluated in the same manner described inExample I. Copy quality is satisfactory.

EXAMPLE XVII Preparation of 3,3'-di(2-methyl indolyl) triselenide

This compound is prepared according to the method described by J.Wilshire, Australian J. Chem. 20, 359 (1967). The product of thissynthesis is recrystallized from hexane/methylene chloride. m. p. 194°-197° C.

An imaging member is now prepared from 3,3'-di(2-methyl indolyl)triselenide and poly(n-vinylcarbazole) in the manner described inExample I. This imaging member is evaluated in the same manner describedin Example I. Copy quality is satisfactory.

EXAMPLE XVIII Preparation of bis(4-methyl-2-nitro-phenyl) triselenide

This compound is prepared according to the procedure described by H.Rheinboldt et al, Chem. Ber. 88, 1 (1955). The product of this synthesisis recrystallized from benzene. m. p. 151°- 152° C.

An imaging member is now prepared from bis(4-methyl-2-nitro-phenyl)triselenide and poly(N-vinylcarbazole) in the manner described inExample I. This imaging member is evaluated in the same manner describedin Example I. Copy quality is satisfactory.

EXAMPLE XIX Preparation of benzyl seleno benzoate:

A solution comprising 3.1 grams of dibenzyl diselenide in 200milliliters of a solution of water/tetrahydrofuran (1:1) is reacted withabout 0.5 grams sodium borohydride under a nitrogen blanket until theyellow color of the diselenide appears to be completely discharged.About 5 grams sodium bicarbonate and about 3 grams benzoyl chloride arenow added to the reaction mixture with agitation. Stirring of themixture continues until the characteristic odor benzoyl chloride isdissipated. The reaction mixture is then extracted with ether and water,the ether solution washed with saturated sodium sulfate, dried overanhydrous sodium sulfate and evaporated to an oily residue. The oilyresidue is crystallized with light petroleum (40°- 60° C) to givecolorless needles, (m. p. 29°- 32° C).

An imaging member is now prepared from benzyl seleno benzoate andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XX Preparation of dibenzoyl selenide

A sodium selenide solution is initially prepared by the reaction ofabout 3.2 grams (0.04 moles) of selenium powder with about 3 grams (0.08moles) sodium borohydride in water according to the method described byD. L. Klayman et al, J. Am. Chem. Soc. 95, 197 (1973). The flaskcontaining the sodium hydrogen selenide solution is purged of air withnitrogen and about 11.2 grams (0.08 moles) benzoyl chloride and about 10grams sodium bicarbonate added to the reaction mixture with mildagitation. The ingredients within the flask are allowed to react at roomtemperature under nitrogen for 14 hours. The solid products areseparated from the reaction medium by filtration, washed with water andrecrystallized from a benzene/hexane solution to yield colorless needlelike crystals, (m. p. 60°- 61° C).

An imaging member is now prepared from dibenzoyl selenide andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XXI Preparation of dibenzoyl diselenide

Preliminary to the synthesis of the above material, an aqueous sodiumdiselenide solution is prepared according to the procedures described byD. L. Klayman et al in J. Am. Chem. Soc. 95, 197 (1973). To thissolution is been added about 28.1 grams (0.2 moles) benzoyl chloride andabout 16 grams sodium bicarbonate. The reaction mixture is stirred for16 hours at room temperature, the yellow solids collected, washed withwater and recrystallized from benzene/hexane to yield a yellowcrystalline material, (m.p. 130°- 132° C).

An imaging member is now prepared from dibenzoyl diselenide andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XXII Preparation of α,α'-dibenzoylseleno toluene

This material is prepared according to the procedures described bySzperl et al, Roczniki Chem. 12, 71 - 77 (1973). The product thusobtained, which is crystallized from carbon tetrachloride, has a meltingpoint of 149°- 150° C.

An imaging member is now prepared from α,α'-dibenzoyl seleno toluene andthe poly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XXIII Preparation of bis(benzoylseleno) methylene

About 17.1 grams poly(methylene oligo selenide) is suspended in 100milliliters 1 N aqueous sodium hydroxide, the vessel containing thesuspension purged of air with nitrogen and about 3.7 grams (0.1 moles)sodium borohydride added to this suspension. Upon the admixture of thesetwo materials, the contents of the flask turns a deep brown however,after reaction at room temperature for about 1 hour the color of thereaction mixture mass progressively lightens. About 75 minutes after theinitial admixture of the two materials in the flask, a total of about 31grams (0.22 moles) benzoyl chloride is introduced into the reactionvessel (in 5 equal portions), the contents of the flask rapidly stirreduntil the characteristic odor of benzoyl chloride has been dissipatedand an oily solid covers the stirrer and walls of the reaction vessel.The contents of the flask are extracted with two 250 milliliter portionsof ether, the ether solution washed with water, and saturated aqueoussodium sulfate. After drying over anhydrous sodium sulfate the solutionis evaporated in a vacuum, leaving an oily partially crystallizedresidue. This residue is taken up in warm ligroin (b. p. 60°- 100° C)and the resulting solution chilled to yield colorless needle likecrystals, (m.p 108° C). Elemental analysis of these crystals confirmsthe product to be bis(benzoylseleno) methylene.

An imaging member is now prepared from bis(benzoyl seleno) methylene andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XXIV Preparation of selenium bis(acetophenone) dichloride

Into a 250 milliliter round bottom flask equipped with an additionfunnel are placed 90 milliliters of anhydrous ether and 14.49 grams(0.12 moles) of acetophenone. The flask is cooled in an ice-methanolbath, and about 10 grams (0.06 moles) selenium oxychloride in 30milliliters of anhydrous ether introduced into the flask by dropwiseaddition through the addition funnel. The mixture is stirred during suchaddition. Upon completion of the introduction of the contents of theaddition funnel into the flask, the flask is removed from the ice bathand the contents stirred at room temperature for an additional 1hour. Atthe end of this interval, a white solid precipitate is separated fromthe contents of the flask by filtration, washed with benzene and etherand rapidly recrystallized from chloroform to yield colorless needlelike crystals, (m. p. 117°- 118° C). Elemental analysis of theprecipitate confirms the product to be selenium bis(acetophenone)dichloride.

An imaging member is now prepared from selenium bis(acetophenone)dichloride and poly(N-vinylcarbazole) in the manner described in ExampleI. This imaging member is evaluated in the same manner described inExample I. Copy quality is satisfactory.

EXAMPLE XXV Preparation of selenobenzamide:

A sodium selenide solution is initially prepared by the processdescribed by Klayman et al (J. Am. Chem. Soc. 95, 197 (1973)), whereinabout 7.8 grams (0.1 moles) selenium is reduced in aqueous suspensionwith about 7.4 grams (0.2 moles) sodium borohydride). After the solutionbecomes colorless, its volume is increased 3 fold by dilution with ethylalcohol (95 percent) and 10.3 grams (0.1 moles) benzonitrile addedthereto. The vessel containing this solution is then sealed, and allowedto stand overnight (approximately 16 hours) at room temperature. Thesolution within the vessel (which subsequently turned orange in color)is diluted with equal parts water and ether, the ether phase collected,the aqueous phase extracted with additional ether, and both ether phasescombined in a single vessel. The ether phase is thereafter dried overanhydrous sodium sulfate, the drying agent removed by filtration and theether phase evaporated thereby yielding an oily crystalline residue.This residue is recrystallized from benzene/hexane (60:40) to yield anorange needle like product (m. p. 126°- 127° C); which is subsequentlyconfirmed by elemental analysis to be the desired product.

An imaging member is now prepared from selenobenzamide andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XXVI Preparation of 2-selenopyridine

This compound is prepared according to the procedure described by H. G.Mautner et al J. Org. Chem. 27, 3671 (1962). The product obtained by theabove method is recrystallized from benzene, (m. p. 132°- 136° C).

An imaging member is now prepared from 2-selenopyridine andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XXVII Preparation of 2,5-dimethyl-3-selenocyanatopyrrole

This compound is prepared according to the procedures described by L. B.Agenas, Ark. Chemi. 28, 145 (1967). The product thus obtained iscrystallized from carbon tetrachloride, (m. p. 104°- 107° C).

An imaging member is now prepared from2,5-dimethyl-3-selenocyanatopyrrole and poly(N-vinylcarbazole) in themanner described in Example I. This imaging member is evaluated in thesame manner described in Example I. Copy quality is satisfactory.

EXAMPLE XXVIII Preparation of p-nitrophenyl seleno cyanate

This compound is prepared according to the method described by H. Bauer,Ber. 46, 92 (1913). The product obtained by this method isrecrystallized from methanol (m.p. 135° C).

An imaging member is now prepared from p-nitrophenyl seleno cyanate andpoly(N-vinylcarbazole) in the manner described in Example I. Thisimaging member is evaluated in the same manner described in Example I.Copy quality is satisfactory.

EXAMPLE XXIX

The procedures of Example I are repeated except that a sheet of NESAglass (tin oxide coated glass plates available from PPG Industries,Inc.) is substituted for the ball grained aluminum substrate. After thepolymeric coating on the NESA plate is substantially free of residualsolvents, it is subjected to blanket UV illumination through the NESAplate. As a result of this exposure, a substantially uniform layer ofselenium is extruded and deposited proximate to the interface of thepolymer coating and the NESA plate. The plate is then evaluated bystandard xerographic techniques as follows: the surface of the polymericcoating is initially sensitized by corona charging to a negativepotential of approximately 600 volts. The sensitized surface of thisimaging member is thereafter exposed to image information. The source ofillumination of the image information is white light. The latentelectrostatic image thus produced is developed and transferred byconventional means, toner residues removed from the surface of thepolymeric coating and the copying sequence repeated. Copy quality issatisfactory.

EXAMPLE XXX

The procedures of Example XXIX are repeated except that instead ofblanket UV exposure of the polymeric coating, a discrete dot imagepattern is projected through the NESA substrate onto the polymericcoating. As a result of such exposure, selenium is extruded anddeposited, in substantial conformity with this discrete image pattern,proximate to the interface of the polymer coating and the NESA plate.The imaging member thus produced is sensitized, imaged and developed inthe same manner described in the foregoing Example. Solid densitydevelopment is improved over Example XXIX and the reproduction hasimproved continuous tonal qualities.

EXAMPLE XXXI

The procedures of Example XXX are repeated except than an optical screenpattern is substituted for the dot pattern. In the projection of thisoptical screen pattern with UV light through the NESA plate, the patternis deliberately thrown slightly out of focus. As a result of suchexposure, selenium is extruded and deposited, in substantial conformityto this screen pattern, proximate to the interface of the polymercoating and the NESA plate. The resulting imaging member is sensitized,imaged and developed in the same manner described in the foregoingExample. Solid density development has improved over that Example XXIXand the dynamic range of this member has been extended beyond that ofthe members of Example XXIX and XXX.

EXAMPLE XXXII

The procedure of Example I are repeated except that a scroll ofaluminized Mylar (polyethylene terephthalate, available from E. I. duPont de Nemour Inc.) is substituted for the ball grained aluminumsubstrate. The aluminized surface of this substrate is coated with apolymeric coating of the type described in Example I. Subsequent tocuring of this coating, the scroll is arbitrarily divided into a seriesof separate sections and each section exposed to one of a series ofimage patterns. The source of illumination of these image patterns is amedium pressure UV lamp of the type used in Example I. The imaged scrollis inserted in a device of the type shown in FIG. I. As the scroll 10advances in the direction indicated by the arrow, it is subjected tosimultaneous charging 11 and exposure 12 to white light. The latentimage thus produced is rendered visible by reverse development atstation 13 and the toner image 14 transferred to a receiving sheet 15.This process is repeated in sequence for each section of the scroll.Since the copies are prepared in sequence, no sorting or collating ofthe reproductions is required.

EXAMPLE XXXIII

About 3 grams dibenzyl diselenide (prepared in the manner described inExample I) and about 10 grams of a styrene/hexyl methacrylate copolymer(80/20) are dissolved in 25 milliliters tetrahydrofuran, and theresulting solution coated on a series of brushed aluminum plates using aGardner mechanical drive film coating apparatus having a wet gap settingof 0.001, 0.002, 0.004 and 0.008 inch. Each of the four plates areallowed to dry overnight at room temperature, exposed to blanket UVillumination with a 450 Watt Hannovia medium pressure mercury lamp froma distance of 10 centimeters for periods ranging in time from 1 to 20minutes, (the more extensive time intervals being required for thethicker coatings). As a result of said exposure, elemental selenium isapparently deposited uniformly throughout the coatings thus coloringthese coatings from a pale yellow orange to deep brown. Plates thusprepared are thereafter sensitized by charging with a corona electrodeto a positive potential of 700 volts. The sensitized plates are exposedto imagewise illumination using a Xerox No. 4 Camera for 10 to 30seconds at f 10. The latent image thus produced is rendered visible bycascade development utilizing Xerox 2400 Toner. Image resolution andcontrast are satisfactory.

EXAMPLE XXXIV

About 2 grams dibenzyl diselenide (prepared as described in Example I)and about 10 grams of a copolymer of styrene/n-butylmethacrylate (70/30)are dissolved in 120 milliliters benzene. The resulting solution isdraw-bar coated on a ball grained aluminum plate in the same mannerdescribed in the preceeding Example. Sufficient solution is transferredto the plate to produce a coating having a dry film thickness in therange of 8 to 10 microns.

The above plate is placed in the target area of an election irradiationunit capable of generating a 30 kilo volt electron beam. The apparatusis thereafter sealed, the target area cooled to liquid nitrogentemperature and the atmosphere within the apparatus exhausted to apressure of about 10⁻ ⁶ Torr. The film is allowed to warm to about 20° Cand irradiated until the coating acquires a light orange color.Irradiation is thereafter discontinued, the vacuum seal broken and thefilm target removed from the apparatus. The electrophotographicproperties of this film are now evaluated by charging the surface with acorona electrode to a positive potential of 700 volts followed byblanket illumination through an appropriate band pass filter at 400 nm.Continuous monitoring of the surface potential of the film with anelectrometer reveals rapid and essentially complete discharge of theapplied surface voltage occurs, indicating the existence ofphotoconductive pathways of selenium from the surface of the film to theconductive aluminum substrate.

The film is then reevaluated in the more conventional manner usingstandard Xerox Model D equipment as described in the previous Example.The film prepared according to this Example is capable of producingsharp clear toner images and is capable of repeated cycling withoutappreciable fatigue.

EXAMPLE XXXV

A series of 3 aluminum plates are coated with a solution of dibenzyldiselenide and poly(N-vinylcarbazole) in the manner described in ExampleI. Each coated aluminum plate is placed in a hood for several hours andthen transferred to a vacuum chamber where it remains overnight.Sufficient solution is transferred to each of the aluminum plates toprovide a coating having a dry film thickness of approximately 10microns. Upon substantially complete removal of residual solvents fromthe coating, each of the coatings is uniformly illuminated withultraviolet light from a distance of 6 inches of a period of 10 minutes.Each of these coated aluminum substrates is preheated on a warming tableto a different temperature prior to enduring such irradiation in orderto demonstrate the effects of thermal energy on the morphology of theselenium deposit. Where the temperature prevailing during photoextrusionof selenium is maintained at about 40° C (FIG. No. 2) the elementalselenium deposits appears as a dense continuous layer (approximately0.07 microns in thickness) of very small (0.01 microns) seleniumparticles located approximately 0.04 microns below the outer surface ofthe coating. There is apparently some selenium deposited on both sidesof this dense compact layer, however, due to the optical density of thislayer ultraviolet light is precluded from penetrating substantiallybeyond the layer and thus little if any selenium is deposited throughoutthe bulk of the film. The same procedure is repeated with a secondcoating (FIG. No. 3) except the temperature prevailing immediately priorto and during such photoextrusion is approximately 60° C. At such highertemperatures, the layer of amorphous selenium appears to form discreteglobules approximately 0.1 microns in diameter. The location of suchglobules is substantially the same as the dense compact layer describedin FIG. 2.

A third plate (FIG. No. 4) is processed in the manner similar to thatdescribed for the plates referred to hereinabove (FIG. Nos. 2 and 3)except that immediately prior to and during exposure to ultravioletlight, its temperature is maintained at About 68° C. At such highertemperatures, amorphous selenium globules not only appear near thesurface of the coating but are nonuniformly dispersed throughout thebulk of the organic polymer film. It is not known whether or not at suchhigher temperatures the selenium globules become mobile and migrate fromimmediately below the surface of the coating into the bulk of the filmor whether or not the precursor compounds within the coating are lessstable and thus more readily undergo selenium-carbon bond sision uponexposure to the ultraviolet light that is capable of penetrating thedense selenium deposit near the surface of the coating.

What is claimed is:
 1. A process for preparation of a solid phasedispersion of inorganic photoconductive materials in an insulatingpolymeric matrix comprising:a. forming a polymeric composition from afilm forming insulating polymeric resin and at least one organo-seleniumcompound of the formula ##STR7## wherein R, R', R", R"' and R^(iv) areindependently selected from hydrogen, alkyl of 1 - 10 carbon atoms,phenyl, substituted phenyl, benzyl, and substituted benzyl; and b.subjecting said polymeric composition to sufficient energy to decomposesaid selenium compound; whereby elemental selenium is deposited in theorganic polymeric composition in substantial conformity with thedistribution of said energy throughout the composition.